Collapsible container



March 29,1960 M. M. CUNNINGHAM ETAL 2,

COLLAPSIBLE CONTAINER Filed Nov. 12, 1957 3 Sheets-Sheet 1 QW War/ZATTORNEY March 29, 1960 M. M. CUNNINGHAM ET AL ,93

COLLAPSIBLE CONTAINER Filed Nov. 12, 1957 I5 Sheets-Sheet 2 INVENTORSMAR/0N M. C Z/IV/V/IVGHAM W/Z L/AM FRASER A TTORNEY March 1960 M. M.CUNNINGHAM ET AL 2,930,423

COLLAPSIBLE CONTAINER Filed Nov. 12, 1957 3 Sheets-Sheet 3 INVENTORSMAR/0N M C U/V/V/A/Gl/AM W/lL/AM PRAG'ER BY ATTORNEY United StatesPatent COLLAPSIBLE CONTAINER Marion M. Cunningham, Providence, andWilliam Prager, Hoxsie, R.I., assignors to United States Rubberglompany, New York, N.Y., a corporation of New ersey ApplicationNovember 12, 1957, Serial No. 695,961

9 Claims. (Cl. 1501) This invention relates to collapsible liquidpackages or storage containers and particularly to packages orcontainers of this type formed by closing the ends of a flexible tube.

In the packaging industry containers are often referred to as packages.Accordingly, in this'application the terms will be used synonymously,and what is discussed with respect to a package for transportationpurposes will also apply to a container for storage purposes.

A simple and inexpensive package or container may be constructed offlexible material merely by forming a tube and closing off both ends byflat clamps. If the material is a rubber or similarly coated cordfabric, the tube may be given any desired size and any desired length byvulcanizing it in a flatly pressed condition, as de scribed in UnitedStates Patent No. 2,381,074, instead of in a round condition. Such atube would have permanent lines of fold along its opposite sides whichwill enable it to lie in a completely flat condition when not inflatedor filled. It may thus be rolled up into a compact package when not inuse, so that great savings are realized in return shipping and storingwhen empty.

Heretofore, containers of this type have been constructed merely byclosing each end of the tube by a straight clamp. When empty, such acontainer collapses into a doubly covered rectangle.

This kind of construction, while having the advantages described above,disregards an important strength characteristic of the cord fabricforming the walls of the container. Whereas this fabric withstandsrepeated moderate bending and subsequent flattening almost indefinitely,a few repetitions of sharp bending and subsequent flattening tend tosplit the plies of the cord fabric and induce premature failure. When acontainer of the construction heretofore described is pressurized,pronounced wrinkles are observed to form in the container walls near theends of the container. During each filling and subsequent emptying ofsuch a container, the wall fabic is sharply bent along these wrinklesand then flattened with the consequent damage to the wall fabric asdescribed above.

The primary object of this invention is to provide a collapsiblecontainer that has the advantages heretofore described but which, incontrast to similar containers proposed so far, is substantiallywrinkle-free. in all degrees of expansion from the completely flatcondition to the fully expanded condition.

In accordance with the present invention, this object is obtained byclosing each end of the tube by two substantially conical extensionshaving their vertices laterally spaced and forming the extremities ofthe container. Also, in accordance with the present invention, it hasbeen found that such substantially conical extensions may be easilyformed by cutting a reentrant angle of approximately 165 and preferablybetween 162 and 168 in the end edges of the tube when the tube is int!2,930,423 Patented Mar. 29, 1960 ice flattened condition and thenclamping or securing the cut edges together.

When a container constructed in accordance with the present invention ispressurized, the cross section of the central portion approaches acircular form. When the container is empty, this central part collapsesinto a doubly covered rectangle. By virtue of the reentrant angle, eachendofthe container takes the form of a pair of cones, the vertices ofwhich are symmetrically and laterally spaced along a common diameter ofthe cylinder and form the extremities of the container. Each end of thetank also will collapse into a doubly covered plane without stretching,creasing or wrinkling.

Thus in the transition from the full to the empty state, the entireflexible material forming the wall of the container is bent but notappreciably stretched, creased or wrinkled. Because of the absence ofpronounced wrinkles caused by pressurization, or internal loading, thecontainer can withstand a practically unlimited number of filling andemptying cycles without damage. A flexible container constructedaccording to this invention will therefore have a much longer usefullife than those heretofore constructed. It will be better able towithstand internal pressure and the abuses to which it is subjected byordinary usage. I a

A container constructed according to this invention can be used forstorage of gases and liquids as well as for their transportation usingit as a package. It can be economically constructed in all sizes andcapacities to meet individual requirements. In liquid transportationservice, the roll-up package feature, making possible a return payloadin space saved, will prove itself very economical. Strong tire-likeconstruction will insure performance with safety.

By having a broad ground contact area this container can be used forstorage where low unit floor loading is a requirement. Also this largefootprint causes the container to be stable during braking oracceleration when used as a liquid package.

A loose interior lining may be used if the nature of the contents makesthis desirable. Emptying in that case can be either by sucking thecontents from an orifice in the container or by introducing air underpressure between the loose lining and the container wall to thus forcethe contents out.

All types of liquids and gases, including corrosive materials, can bestored and transported in this package. It is particularly well suitedto viscous liquids like molasses.

This package will make any highway truck also a liquid carrier and, onrailroads, any flat car or gondola car a liquid carrier. For storage itreplaces the rubber-lined metal tank in that it is its own structure. p

When inflated with air, it can be used as a chock to prevent othercontainers from moving during transportation. Its adjustable diameter,obtained by different degrees of inflation, will make thechock fit anytruck or railroad bodys unfilled width.

For a better understanding of these 'and other characteristics andadvantages of the present invention, refer]- the method of sealing and atype of segmented clamp that can be used for same;

Fig. 5 is a schematic view of the general method used for closing theends of the tube to form the container;

Fig. 6 is a detail of a segmented rotatable clamp that can be used toclose the ends of our container, showing the method of running the cordsof the fabric underneath the clamp, and with one of the plies brokenaway to show the ply underneath; and

Fig. 7 is a cross-sectional view along line 77 of Fig. 6, the solidlines indicating the container walls when empty and the dotdash lineswhen inflated or full.

Referring to the drawings there is shown the flexible container of thisinvention having a cylindrical body portion 10 and closed at the ends bya pair of cones 11 and 12 which form a reentrant angle 13 in the ends. Afilling opening 14 may be disposed in one end of the container as shown.Closing fixtures consisting of segmented plates or clamps 15 grip thefabric and bind it both laterally and axially at the end portion andthus effect the closure. If only two rigid plates are used to close theends of the container, they must be hinged together at the vertex 13 ofthe reentrant angle and thus cause concentrated lateral flexing. If,however, a number of clamps 15 are used to close the ends of thecontainer, they may be disposed so as to permit individual rotation andconsequent change in the reentrant angle 13 as the pressure or loadinginside the container varies, as illustrated in Fig. 2.

The walls 16 of the container as shown in Fig. 3 are formed of aplurality of layers of cord fabric. Since a single layer of cord fabrichas strength in the warp direction only, several plies are used to builda wall in which each ply has its warp yarns placed at a substantialangle to the warp yarns of the adjacent layers so that the wall hastwo-directional strength. This equal ply construction is well known inthe tire industry. The inner and outer layers of cord fabric of thewalls of the container may becoated with a heavy surface layer of rubberor other suitable material to protect the cord fabric against thematerial to be shipped or stored in the package as well as againstexternal abrasions.

Various techniques of manufacture are possible. The container may bemade by winding cord on a mandrel in a continuous helix, covering theindividual cords with rubber or similar material and vulcanizing. Orrubber coated cord cord fabric may be cut on the bias of the fabric,plied up, rolled into a cylindrical shape and seamed. Curing may be inthe fiat or as a cylinder.

Fig. 5 shows the basic method chosen for closing the tube 10. The axisof the cylindrical portion 10 of the container should be visualized asbeing horizontal. The cylindrical part 10 of the tube is bounded on theleft by the circle ABC, whose plane is perpendicular to the axis. In thehorizontal plane through the axis, points V and V are symmetricallysituated with respect to this axis. These points are used as thevertices of two cones 11 and 12 both based on the circle ABC.

It was found that when a reentrant angle 13 of approximately 165 is cutin the ends of the flattened tube as shown by the solid line in Fig. 2and the said ends are clamped or otherwise secured together with a hingemotion possible at the reentrant angle apex13, the two cones 11 and 12thereby formed at theextremities of the container are so located as toresult ina geometrical structure which is approximately developable.Thus, this configuration of end cones 11 and 12 gives a container whichwill be substantially wrinkle-free at all degrees of inflation.

The reentrant angle of 165 was found to be the optimum angle for closingthe tube 10 by merely clamping the ends. This angle can be rounded offby a fillet in the actual construction of the container. 'It isrecommended, for instance, that a fillet radius of approximately inchesbe used for a container diameter of approximately 10 feet.

As the end cones are based on the circle ABC in Fig. 5, theirintersections with any plane that is perpendicular to the axis of thetank will be circular. Thus, if the vertex of one of the end cones becut off perpendicular to the axis of the tank, this cut will form acircular filling hole 17 as shown in Fig. 4.

The design of the seams at the ends of the container must take intoconsideration that the reentrant angle 13, which for a container ofoptimum configuration is 165 in the empty condition, decreases toapproximately when the tank is completely filled, as shown by the dottedline in Fig. 2. The corresponding freedom of motion can only be assuredby a hinge at the reentrant corner 13. It should be understood thattheoretically only two straight clamps are needed to close each end,these clamps being hinged at the reentrant corner 13. The segmentedclamps 15 shown in Fig. 4 are advantageous when it is considered thatthe resulting structure is not rigorously developable. Rotation of theseclamps 15 can compensate for the slight excesses and deficiencies ofwall material 16.

Figs. 6 and 7 illustrate a type of rotatable clamp 15 that has beenfound satisfactory. One edge 19 is curved outwardly to avoid injuringthe wall material as the container expands. The cords of the materialforming the container walls run under several of the clamps 15, as shownin Fig. 6, thereby effecting a secure closure. Although two straightclamps broken at the apex of the reentrant angle 13 are necessary, if itshould prove impossible to design a hinge which maintains a tight sealwhile allowing the necessary rotation, the bending theoreticallylocalized at the corner 13might be distributed over a greater length byrounding out this corner more generously. In any case, the width of theclamp 15 at the end should be reduced to a minimum to avoid crinkling atthe outer edge of the seam.

A loose lining 18 as shown in Fig. 3 may be used with this container ifthe nature of the contents makes this desirable. Its position 18a whenpartially emptied is also indicated in Fig. 3. The emptying can beeffected either by sucking the contents out through the opening 14 or byintroducing air under pressure through opening 14:: to force thecontents out.

From the foregoing it is apparent that we have devised a storage orshipping package which has a good practical construction, in that it maybe handled, stored and return shipped easily, yet which will givegreatly improved wearing qualities and should have a very long life inuse. In particular, this container may be made substantially cylindricalin shape, yet free of compressive stresses and the resulting wrinkles.These advantages are achieved by abandoning the tube with a straightclosed end and substituting in its place the reentrant angle of thepresent invention.

Although a specific embodiment of a container according to thisinvention has been described, it is our intention to cover all changesand modifications of the example of the invention herein chosen forpurposes of the disclosure, which donot constitute departures from thespirit and scope of the invention.

Specifically, although in the description of this structurea rubberizedcord fabric is described, it will be appreciated that the walls ofthe'container may be madeup of any flexible material, and that'acontainer according to this invention could be made irrespective of thenumber of plies of the material forming its walls.

Also, although it has been found that is the optimum size for thereentrant angle, variations in this angle will not constitute adeparture from the spirit and scope of the invention.

Having thus described our invention, what we claim and desire to protectby Letters Patent is:

1. 'A collapsible'container formed of relatively flexible materialcomprising a substantially cylindrical body portion, the opposite halvesof the marginal edges of each end of said cylindrical body portion beingprovided with reentrant angles, said opposite halves of said marginaledges being secured together to close each end of said container., 7 v

2. A collapsible container as defined in claim 1 in which said containeris of tubular form and said reentrant angles are approximately 165 whenthe said container is in a flattened condition.

3. A collapsible container as defined in claim 1 in which said halves ofsaid marginal edges are secured together by rigid clamping means, saidrigid clamping means being hinged together at least at the apex of saidreentrant angle.

4. A collapsible container as defined in claim 3 in which said rigidclamping means form a reentrant angle of between 162 and 168 when thesaid container is in a flattened condition.

5. A collapsible container as defined in claim 1 in which said halves ofsaid marginal edges are secured together by a plurality of rotatableclamps.

6. A collapsible container as defined in claim 5 in which said marginaledges form a reentrant angle of between 162 and 168 when the saidcontainer is in a flattened condition.

7. A collapsible container formed of relatively flexible material, saidcontainer having a substantially cylindrical body portion closed at eachend by a pair of substantially conical extensions, the vertices of saidconical extensions being laterally spaced along a common diameter ofsaid cylindrical body portion and forming the axial extremities of saidcontainer, whereby said container is substantially developable and willbe substantially free of wrinkles at all degrees of inflation, a looseliner in said container, an opening through said liner and container forfilling and emptying said container, and a second opening through saidcontainer spaced fromsaid first opening for introducing gas underpressure between the wall of said container and said liner, tocjcollapsesaid liner and force the contents of said liner out of said firstopening.

8. A collapsible container formed of a coated cord fabric, saidcontainer having a substantially cylindrical body portion closed at eachend bya pair of substantially conical extensions, the vertices of saidconical extensions being laterally spaced along a common diameter ofsaid cylindrical body portion and forming the axial extremities of 'saidcontainer, whereby said container is substantially developable and willbe substantially free of wrinkles at all degrees of inflation.

9. A collapsible container formed of a plurality of layers of coatedcord fabric, wherein the cords of one layer form an angle with the cordsof adjacent layers, said container having a substantiallyjcylindricalbody portion closed at each end by a pair of substantially conicalextensions, the vertices of said conical extensions being laterallyspaced along a common diameter of said cylindrical body portion andforming the axial extremities of said container, whereby said containeris substantially developable and will be substantially free of wrinklesat all degrees of inflation.

References Cited in the file of this patent UNITED STATES PATENTS

